Proteinases secreted by macrophages are implicated as mediators of the inflammatory response and related destruction of connective tissue macromolecules. The aim of this proposal is to purify and characterize the molecular structure and regulation of macrophage elastase (ME), a neutral metalloproteinase secreted by inflammatory macrophage. During preliminary characterization and purification of ME multiple molecular forms of the enzyme have been resolved - a 22 Kilo dalton form and a 42 Kilo dalton form. The 42K form that is activated 8 to 10 fold during assay with elastin in the presence of sodium dodecyl sulfate may be a latent ME while the 22K form is active ME. My primay emphasis will be to purify the 42K ME, to study the interrelationships of the 42K and 22K forms and to prepare heterologous and monoclonal antibodies to the ME forms. The antibodies will facilitate affinity purification of ME for structural and biochemical studies and for monitoring biosynthesis of ME forms by macrophages in different states of differentiation and activation. Homogeneous preparations of ME will make it possible to study the role of ME in the proteolysis of plasma and connective tissue proteins in addition to elastin. In particular the influence of ME degradation of immunoglobulins (IgG2a, IgG2b, and IgM) on macrophage C3b and Fc-receptor mediated binding will be evaluated. Because of the multiple functions of ME in limited proteolysis of humoral and extracellular matrix proteins, these studies should give us new insights into the role of macrophages in the pathophysiology of inflammatory and connective tissue diseases of the lungs and vasculature.